1. Field of the Invention
This invention relates generally to safety devices for warning persons working upon a roof that they are getting dangerously close to an edge of same.
2. Description of the Prior Art
It is a safety requirement that workmen working on a roof, either applying a new roof system or repairing or remodeling an old roof system, be protected from falling from the roof perimeter.
Several methods are commonly used to protect a workman from falling off the roof perimeter. One is to place a safety line to which the workman can fasten to while working on the roof, and another is to provide a warning line to remind the workman that he is near the roof perimeter.
One method used today on pre-engineered building roof panel placement for the edge of the roof workman protection is a rope or chain marked with colorful banners which is a warning line to remind the workman of the roof edge. Although the line is helpful as a reminder, the line is constantly in the workman's way while applying roof material, which is a great disadvantage.
Also, it is known in the art to utilize beams of light, including lasers, to act as safety or protection devices in association with areas to be guarded; however, the inventor is not aware of any art utilizing such a concept for a safety device in conjunction with the perimeter of a building roof, and especially with structure which can be attached to the existing sections of a roof, the roof panel support purlins, the end sections and edges of the roof, and the like.
Existing prior patents which may be pertinent to the present invention are as follows:
U.S. Pat. No. 3,623,057--R. A. Hedin, et al.--11/23/71 PA1 U.S. Pat. No. 3,653,021--C. Litman, et al.--3/28/72 PA1 U.S. Pat. No. 3,825,916--R. K. Steele, et al.--7/23/74 PA1 U.S. Pat. No. 4,004,805--K. Chen, et al.--1/25/77 PA1 U.S. Pat. No. 4,186,388--D. W. Robinson--1/29/80 PA1 U.S. Pat. No. 4,408,195--B. J. Tullis, et al.--10/04/83.
U.S. Pat. No. 3,623,057 to Hedin, et al. discloses the use of laser beam apparatus for protecting the perimeter of a predetermined geographical area. However, this device is mounted upon the ground or similar floor surface, and fails to provide any structure whatsoever for use of same with the roof of a building being constructed and/or repaired.
The patent to Litman, et al., U.S. Pat. No. 3,653,021, shows apparatus having a base attachable to a surface for containing light beam structure therewithin; however, the specific construction is entirely different from that disclosed in the present application.
The patent to Steele, et al., U.S. Pat. No. 3,825,916, shows another line-of-sight light beam utilizing infrared energy generated from a solid state source. Again, this device is used to form a fence for protecting or detecting intrusion of a predetermined area. The structure again is entirely different from that of the present invention.
U.S. Pat. No. 4,004,805 to Chen, et al. discloses the use of double beam laser apparatus for defining the service lines and boundaries of tennis courts for monitoring the tennis ball and the players during the playing of a game. While specific electronic circuitry is disclosed, nothing relating to use of such apparatus for protection on a roof is taught.
U.S. Pat. No. 4,186,388 to Robinson shows a proximity detector utilizing specific elevatable tripod structures, as best seen in FIG. 1 of the patent. While this structure is somewhat related to that disclosed by the present invention, there are substantial differences thereover.
The patent to Tullis, et al., U.S. Pat. No. 4,408,195, discloses the use of a laser transmitter for emitting a beam which can be scanned about a scanning axis to effect a curtain of light which defines a boundary of a working space. If the outboard portion of a crane or other construction equipment moves into the light curtain, appropriate warning signals to the operator and nearby personnel are effected. Again, the structure disclosed in this patent is substantially different from that of the present invention.
None of the known prior art devices and systems offer the new and novel features of the present invention.